Jailbroken iPhones only: Brazilian developers Daniel Antonio and Alexandre Kremer have a nifty application for the iPhone, iBlacklist, which allows you to send particular callers directly to voicemail. And by "particular callers," I mean "your ex." Also: collection agencies, micromanager bosses, your mother who just doesn't approve. You get the picture. At only $12, it's a lot cheaper than an hour with a shrink to maintain your sanity. Other features include the ability to filter out SMS notfications from certain number, and even set up scheduled times when calls won't be let through (particularly useful for keeping your weekends boss-free). But what about those of us who don't have an iPhone?Simply change the name of a contact to "Do not answer." Do not, repeat, do not include the name of the contact. Because then you might hem and haw, maybe even feel a bit guilty when you hit "ignore" and send them to voicemail. The goal is for an automatic response. Call comes in; "Do not answer" appears as the caller ID; press ignore. No muss, no fuss, and it works on any cellphone. Everyone has someone they'd rather not talk to right now, or possibly ever. How do you keep them from getting all up in your phone's business? Let us know in the comments. In the meantime, iBlacklist is available for $12 in the iTunes App Store on jailbroken iPhones only via Cydia. If you haven't jailbroken your iPhone, yet here's how (Mac, Windows).